Heterogenous catalysts have a variety of known applications, in diverse fields including commodity chemicals and fine chemicals. It has long been recognized, however, that the catalytic activity and/or selectivity of heterogeneous catalysts can vary substantially due to many factors. Factors known to have a potential effect on catalytic activity and/or selectivity are described, for example, by Wijngaarden et al., xe2x80x9cIndustrial Catalysisxe2x80x94Optimizing Catalysts and Processesxe2x80x9d, Wiley-VCH, Germany (1998).
Combinatorial (i.e., high-throughput) approaches for evaluation of catalysts and/or process conditions are also known in the art. See, for example, U.S. Pat. No. 5,985,356 to Schultz et al., U.S. Pat. No. 6,004,617 to Schultz et al., U.S. Pat. No. 6,030,917 to Weinberg et al., U.S. Pat. No. 5,959,297 to Weinberg et al., U.S. Pat. No. 6,149,882 to Guan et al., U.S. Pat. No. 6,087,181 to Cong, U.S. Pat. No. 6,063,633 to Willson, U.S. Pat. No. 6,175,409 to Nielsen et al., and PCT patent applications WO 00/09255, WO 00/17413, WO 00/51720, WO 00/14529, each of which U.S. patents and each of which PCT patent applications, together with its corresponding U.S. application(s), is hereby incorporated by reference in its entirety for all purposes. Considered individually and cumulatively, these references teach the synthesis and screening of arrays of diverse materials, and generally, of spatially-determinative arrays of diverse materials. Typical approaches involve primary synthesis and screening (high-throughput xe2x80x9cdiscoveryxe2x80x9d screening) followed by secondary synthesis and screening (more moderate-throughput xe2x80x9coptimizationxe2x80x9d screening), and optionally, followed by tertiary synthesis and screening (e.g., typically traditional xe2x80x9cbench scalexe2x80x9d screening). These references also describe screening strategies in which compositionally-varying arrays are prepared (e.g., as part of a primary or secondary screen) first with broadly-varied gradients. Subsequently, xe2x80x9cfocusedxe2x80x9d libraries comprising more narrowly-varied gradients are prepared and screened (e.g., at the same level of screen) based on the results of the first screen. Such libraries or arrays of diverse materials such as catalysts can comprise binary, ternary and higher order compositional variations. See, for example, WO 00/17413 (as well as its corresponding U.S. application, Ser. No. 09/156,827 filed Sep. 18, 1998 by Giaquinta et al.) and WO 00/51720, (as well as its corresponding U.S. application, Ser. No. 09/518,794 filed Mar. 3, 2000 by Bergh et al.), each of which U.S. and PCT applications are hereby incorporated by reference in its entirety for all purposes. High-throughput process optimization, including process optimization in parallel flow reactors has also been described. See, for example, WO 00/51720, (as well as its corresponding U.S. application, Ser. No. 09/518,794 filed Mar. 3, 2000 by Bergh et al), and additionally, U.S. patent applications Ser. No. 60/185,566 filed Mar. 7, 2000 by Bergh et al., Ser. No. 60/229,984 filed Sep. 2, 2000 by Bergh et al., Ser. No. 09/801,390 filed Mar. 7, 2001 by Bergh et al., and Ser. No. 09/801,389 filed Mar. 7, 2001 by Bergh et al., each of which U.S. and PCT applications are hereby incorporated by reference in its entirety for all purposes.
The efficiency of a catalyst discovery program is, in general, limited by rate-limiting steps of the overall process work flow. Additionally, high throughput approaches still require substantial efforts to explore vast compositional space. As such, current approaches, while offering substantial advances over previous traditional, lower-throughput approaches, can still be improved with respect to overall efficiency. Hence, there is a need in the art for improved overall research work flows for developing and evaluating heterogeneous catalysts for a particular reaction of interest. In particular, a need exists for more efficient, meaningful approaches for identifying new heterogeneous catalysts.
More specifically, a need exists for improved preparation protocols for heterogeneous catalysts. Although substantial advances have been made with respect to parallel synthesis of catalyst candidate materials, and with respect to reaction-based screening of such catalyst candidates, relatively fewer advances have focused on pretreatment of heterogeneous catalystsxe2x80x94after synthesis of the catalysis material or precursor thereof and before screening thereof. Typical post-synthesis catalyst treatment can include chemical treatment (e.g., precursor decomposition, oxidation, reduction, activation), physical treatment (e.g., calcining, washing), and/or mechanical treatment (e.g., grinding, pressing, crushing, sieving, and/or shaping).
Mechanical pretreatment approaches have been effected to date for combinatorial catalysis research using conventional approaches. For example, Senkan et al. reported the preparation of a combinatorial array of shaped catalysts (pellets) using conventional, serial die-pressing. See S. Senkan et al., xe2x80x9cHigh-Throughput Testing of Heterogeneous Catalyst Libraries Using Array Microreactors and Mass Spectrometryxe2x80x9d, Angew. Chem. Intl. Ed., Vol. 38, No. 18, pp.2794-2799 (1998). Grinding approaches for catalyst preparation are also known in the art, including both serial and parallel grinding protocols. (See, for example, Obenauf et al., Catalog of SPEX CertiPrep, Inc. (Metuchen, N.J.) pp. 28-39, 90-91, 104-105 and 114-119 (1999)). Schuth et al. disclose a loading device for synthesis of an array of catalysts, where the loading device is adapted for parallel transfer of the synthesized catalysts to a parallel flow reactor through a communition device. (See EP 19809477 A1). However, such conventional pretreatment protocols, such as the conventional serial pressing approaches, are not efficient enough for preparing arrays comprising larger numbers of catalysts. Moreover, conventional grinding or communiting approaches, although parallelized, suffer from other deficiencies. Such grinding approaches, as exemplified for example by the aforementioned communition protocols of Schuth et al, result in a to-be-tested catalyst candidate that includes a broad, uncontrolled distribution of catalyst particle sizes, including catalyst particle fines. Variations in the particle size distribution of candidate catalystsxe2x80x94as compared between reaction vessels (or channels) of a parallel reactorxe2x80x94can affect catalyst performance and, additionally or alternatively, can affect the flow-characteristics when screening the catalysts in a parallel flow reactor, such that in either case, direct comparison of catalysts between reaction vessels or channels is compromised. As such, there remains a need in the art to overcome such deficiencies.
It is, therefore, an object of the present invention to provide for more efficient protocols and systems for effecting mechanical treatments of materials, and especially, mechanical treatment of catalysis materials such as heterogeneous catalysts and related materials.
Briefly, therefore, in one embodiment, the invention is directed to methods and apparatus for preparing an array of materials, preferably diverse materials such as diverse catalysis materials, having a particle size distribution substantially within a predefined particle size range. Four or more materials, preferably four or more diverse materials such as diverse catalysis materials (e.g., catalysts, catalyst precursors and catalyst supports) are simultaneously crushed in four or more spatially discrete crushing zones of a parallel crusher. The four or more materials are simultaneously sieved through a first primary sieve as they are being crushed, and additionally or alternatively, intermittently between repeated crushing steps, such that in either case, for each of the four or more catalysis materials, smaller, first-sieved particles pass through the primary sieve whereas larger unsieved particles are substantially retained in the crushing zone for further crushing. If desired, the four or more materials can be simultaneously fractionated, for example, by then simultaneously sieving the first-sieved particles of each of the four or more materials through a second, secondary sieve, such that for each of the four or more materials, smaller, second-sieved particles pass through the secondary sieve whereas larger first-sieved particles are retained by the secondary sieve. As such, primary fractions of each of the four or more materials are formed, with the primary fractions having a particle size distribution substantially within a particle size range ranging from about the mesh size of the secondary sieve to about the mesh size of the primary sieve.
In a related embodiment, the invention is directed to an apparatus for parallel crushing and sieving of catalysis materials. The apparatus generally comprises a crusher body comprising four or more spatially discrete apertures or wells. Each of the four or more apertures or wells define a crushing zone having an interior crushing surface. One or more crushing elements (e.g., crushing media) are located at least partially within each of the crushing zones and are adapted for crushing materials residing in one of the four or more crushing zones. One or more primary sieves can be integral with the crusher body, and/or can define at least a portion of the interior crushing surface for each of the four or more crushing zones, and are generally adapted to simultaneously sieve each of the four or more materials as they are being crushed, or intermittently between repeated crushing steps (e.g., temporally serial cycles of crushing, sieving, crushing, sieving, etc.), such that for each of the four or more materials, smaller, primary-sieved particles pass through the primary sieve whereas larger, unsieved particles are retained in the crushing zone for further crushing.
In some aspects of this embodiment, where further fractioning is desired, the apparatus can further comprise a sieve body comprising four or more spatially discrete apertures corresponding in spatial arrangement to the four or more apertures or wells of the crusher body, with each of the four or more apertures of the sieve body having an inlet end adapted to receive primary-sieved particles passing through the primary sieve, and an opposing outlet end. One or more second secondary sieves is situated substantially at the outlet end of each of the four or more apertures of the sieve body. The one or more secondary sieves is adapted to simultaneously sieve the primary-sieved particles of each of the four or more catalysis materials, such that for each of the four or more catalysis materials, smaller secondary-sieved particles pass through the secondary sieve whereas larger primary-sieved particles are retained by the secondary sieve. The one or more primary sieves have an actual mesh size (i.e., actual opening size of the mesh) that is larger (i.e., smaller mesh-size number) than a mesh size of the one or more secondary sieves, such that primary fractions of each of the four or more catalysis materials can be formed in the apparatus. The primary fractions can have a particle size distribution substantially ranging from about the mesh size of the secondary sieve to about the mesh size of the primary sieve.
In another aspect, the invention is directed toward a method for preparing an array of catalysis materials, where four or more materials such as diverse materials, preferably diverse catalysis materials are simultaneously pressed in four or more pressing zones of a parallel press. The parallel press can preferably be a die press, an isostatic press or a roller press.
The invention is directed as well to a parallel press. The parallel press can comprise a press body comprising four or more spatially discrete apertures or wells, each of the four or more apertures or wells defining a pressing zone, and one or more pressing elements (e.g., pressing membranes, rollers, dies) adapted to simultaneously press each of four or more materials in the four or more pressing zones.
The methodologies and apparatus described and claimed herein also have application for parallel mechanical treatment of catalysis materials as well as other materials. It is contemplated and specifically considered to be part of the invention that the protocols and apparatus disclosed herein are applicable to materials generally, and to other specific categories of materials such as electronic materials (e.g., phosphors), colorants (e.g., organic or inorganic pigments), filtration materials, adsorbents, absorbents, separation media (e.g. for liquid chromatography), fluidizable particles (e.g., for fluidized bed reactors), titania (or other ceramic) nanoparticles, and pharmaceuticals (e.g, crystalline materials having pharmaceutical activity), among others.
Other features, objects and advantages of the present invention will be in part apparent to those skilled in art and in part pointed out hereinafter. All references cited in the instant specification are incorporated by reference for all purposes. Moreover, as the patent and non-patent literature relating to the subject matter disclosed and/or claimed herein is substantial, many relevant references are available to a skilled artisan that will provide further instruction with respect to such subject matter.